1. Field of the Invention
The invention relates to a method and a device for measuring and controlling the circulation of fluids in endoscope channels, directed to verifying and recording the flow of cleaning, disinfecting, rinsing, and drying solutions passing through each of the endoscope channels during operations adapted to clean and disinfect them.
2. Discussion of Background Information
Endoscopes 1 (FIG. 1) are apparatuses used in hospitals. They comprises a control box 2 at one of the ends of an exploration tube 3 adapted to be inserted through a natural conduit into an inner cavity of a patient's body in order to perform the diagnosis of lesions or certain treatments such as, for example, extracting foreign bodies, destroying tumors by coagulation or resection, introducing medicines or substances that are impervious to x-rays. The exploration head is connected by a second tube 4 to a proximal portion 5 comprising a series of injection couplings 6.
These are complex apparatuses comprising in a same tube optic fibers guiding the light coming from a generator, optic fibers carrying images or a video sensor (CCD), as well as various channels, such as operating channels, suction channel, air insufflation channel, water insufflation channel, erecting channel, washing channel. To make the endoscope compact, some of them can be joined in their downstream portion so as to form a single channel. For example, this may be the case for the air and water channels which form a common channel over the last centimeters of the insertion tube of the endoscope, and for the operating channels that join the suction channel. The flows circulating in the endoscope can also be mixed in a chamber (piston cage) having the same number of inlets and outlets.
The real difficulty in cleaning and disinfecting these apparatuses relates to these inner channels in which the circulation of the fluids can be non-existent or inefficient due to their diameter (0.5-4 millimeters). Insufficient pressure does not allow the passage of the solutions, and too much pressure can damage the channels. Furthermore, in view of the interrelation of the channels, it is difficult for the operator to ensure that the circulation of the fluids was sufficient in each channel portion. It is then impossible to ensure that the washing and disinfecting processes were efficient.
To ensure that the various commercially available cleaning and disinfecting processes are efficient, whether they are manual or automated, it is necessary to perform samplings in each of the portions of the channels. To this end, a trained technician (generally a hygienist or a pharmacist) circulates sampling solutions directed to a syringe. These solutions are capable of detaching germs that may remain on the walls of the endoscope channels, and of neutralizing possible disinfectant residues that could vitiate the sampling results.
This handling is constraining as it requires irrigating each of the inlets of the various endoscope channels, one after the other, with all of the possible risks of contamination associated with the handling. It also requires rinsing and disinfecting the endoscope again.
Due to the cumbersomeness of this handling and of the protocol associated therewith, and the need to use trained technicians, who often are in a limited number in the hospital, these samplings are rarely performed.
An automated system for cleaning and disinfecting flexible endoscopes has been previously described in the French Patent No. 2 705 896. It makes it possible to circulate the fluids in the outer portions of the endoscope, as well as independently in each of the inner channels of the endoscope. However, this system does not make it possible to automatically ensure that the cleaning/disinfecting/rinsing/drying fluids have indeed circulated in each portion of each channel. If the endoscope is incorrectly coupled to the automaton, or if the one or several channels are partially or completely closed, the flow and concentration of the cleaning/disinfecting/rinsing/drying solutions through the endoscope, as well as the dwell time can be substantially reduced or even eliminated, resulting in an incomplete disinfection of the instrument.
With respect to safety for the patient, this is currently the most significant flaw in machines of this type. That is the reason why the operators are required to first ensure that none of the channels is closed, and to verify at the end of the cycle that the channels are properly coupled.
Nonetheless, certain automatons have been equipped with flow meters or pressure sensors in order to control the flow or the pressure in each of the channels. All of these methods attempt to determine the volume circulating in the channels in a time unit. The volume is deducted from the interpretation of a measuring sensor (pressure drop, number of impulses of a wheel).
However, these solutions encounter a number of problems:
They are expensive, as they require as many sensors as channel portions to be controlled (up to 8 depending on the endoscopes).
In order to allow for an accurate control, the flow or pressure delivered at the inlet of the channels cannot be optimized. As a result, the control times are long, up to several minutes per channel controlled, which can increase the total time of the cycles.
They do not guarantee that a minimum volume corresponding to the saturation of the channel controlled has indeed circulated in the channel.
The diagnosis of a proper circulation in the channel only relies on the indications provided by a single sensor. The failure of this sensor can cause a serious diagnosis error.
Finally, they require frequent calibrations, and in view of the diverse types of channels, from one mark to the next, the adjustments of the thresholds turn out to be compromises. These adjustments set off false alarms that lead the users to frequently deactivate these safety mechanisms.